Is ${481680}$ divisible by $4$ ?
Solution: A number is divisible by $4$ if the last two digits are divisible by $4$ . [ Why? We can rewrite the number as a multiple of $100$ plus the last two digits: $ \gray{4816} {80} = \gray{4816} \gray{00} + {80} $ Because $481600$ is a multiple of $100$ , it is also a multiple of $4$ So as long as the value of the last two digits, ${80}$ , is divisible by $4$ , the original number must also be divisible by $4$ Is the value of the last two digits, $80$ , divisible by $4$ Yes, ${80 \div 4 = 20}$, so $481680$ must also be divisible by $4$.